Recently, audio, video and data broadcasts are transmitted by a digital system instead of the conventional analog system. So, many efforts have been made to research and develop devices for transmitting and displaying the audio, video and data broadcasts. And, the devices have already been commercialized in part. For instance, a system for digitally transmitting audio broadcast, video broadcast, data broadcast and the like is so-called digital broadcasting. As the digital broadcasting, there is digital audio broadcasting, digital multimedia broadcasting, or the like.
The digital broadcasting is advantageous in providing various multimedia information services inexpensively, being utilized for mobile broadcasting according to frequency band allocation, creating new profit sources via additional data transport services, and bringing vast industrial effects by providing new vitamins to a receiver market.
Many technologies for signal compression and reconstruction have been introduced and are generally applied to various data including audio and video. Theses technologies tend to evolve in a direction for enhancing audio and video qualities with high compression ratio. And, many efforts have been made to raise transmission efficiency for the adaptation to various communication environments.
Generally, an audio signal can be generated by one of various coding schemes. Assuming that there are bitstreams encoded by first and second coding schemes, respectively, a decoder suitable for the second coding scheme is unable to decode the bitstream decoded by the first coding scheme.